waynesulak

I downloaded the instructions and it appears that for a 68mm BB, you should use one spacer on the stokers left (sync chain) side and two on the right (drive) side. This matches my memory of an extra spacer on the drive side. Unfortunately the PDF is too large to attach to a forum post. In any case it should be the same as the instructions that you have. A 73 mm BB uses zero spacers on the left side and one on the right so it maintains one additional washer on the right (drive) side.

If needed and possible I would move a spacer to the other side to get the same lateral measurement.


Wayne

chojn1

Wayne,
My crankset only came with 2 spacers, so I interpreted the instruction to mean 2 on the right and none on the left. I think I will wait for the build out then do what ever it takes to line up the chain line and keep the pedals symmetrical.

Akexpress,
Thanks for the info. I think I will use the groves for the essentric shell, but probably will bend a tube beneath the rear bottom bracket for the front derailleur cable. Do you have any problem with wear on the carbon groves? I am a little weary of a tension-ed braided cable rubbing constantly against carbon fiber.

On another note, which hand is better control for the front brake? And, should the derailleur cables cross before the top tube and re-cross below the boom? Or is it better to stay on the same side all the way.

Thanks again,
CJ

merlinextraligh

Actually there's not a right answer, the convention in the U.S. is that the front brake is operated by the left hand on bicycles. My understanding is that it's reversed in some other places in the world.

Motorcycles are teh reverse, with the front brake being operated by the right hand. Hence, some motorcyclists set their bicycles up to have the front brake on the right hand.

However you do it, its a good idea to be concistent across all your bikes. So if you have single bikes with a left hand front brake, I'd stay with a left hand front brake.

As for the derailluer cables, I'd stay on the same side in front of the head tube, as well as under the BB, given that would appear to result in a bit less lcable friction.

I went back and looked at pics of our bikes, and all of them, ones I built up myself, and ones the shop built up are all done that way.

waynesulak

In the past I have built up our bikes with the cable all on the same side. Later I decided that with cable under the bar tape crossing in front of the head tube to the cable stop on the opposite side results in less stress on the cables. For example when turning the bars as if turning the bike left the cable on the left side seems to handle the turn better than with the cable on all on the same side. To get the cable back on the correct side I cross cable under the bottom tube. On singles I cross it under the down tube. The angle is very slight especially on tandems.

To a certain extend this depends on how you like the cable to look. Both methods worked well for me.

merlinextraligh

Ok, I'm totally confused now.

The OP was proposing crossing the cables in front of the head tube, and then recrossing the the cables underneath the down tube.

The pick in your link shows the cables not crossing in front of the head tube, (for the purpose of not rubbing on the head tube) but then crossing the bare cable underneath the down tube.

What I don't get is that if the cable housings don't cross in front of the head tube, the cables don't have to cross under the bike; i.e. the right shifter controls the RD, running down on the right side of the head tube, staying right of the FD cable nderneath the bike, and running to the RD on the right chain stay.

The FD cable starts on the left shifter, the cable stays to the left of the head tube, left of the rd under the bike, and threads up behind the BB to the FD, without crossing the RD cable.

My bikes are set up with the cable housing as shown in the pick, but I'm pretty certain the cables don't cross underneath. I'll have to look when I go home.

merlinextraligh

Actually, you can see it in this pic. Housing stay on the same side of the head tube, and don't cross underneath the bike. If you crossed them at the head tube, then they would cross underneath, and they'd pull through the cable guides, bending at an angle when they hit the guide. So I don't get the illustrations in the link above.

waynesulak

I have deleted the pic in the previous post because it is confusing. My cabling has the right shifter cable crossing the head tube, and then recrossing under boom or bottom tube. Interestingly both my Santanas' and the Comotion I previously owned have the rear brake cable stop on the left side of the top tube. Since it is standard in the US to have the rear brake controlled by the right lever, that cable must cross the head tube. It appears your pic above also has the rear brake cable crossing the head tube.

merlinextraligh

Yes, the rear brake crosses the head tube. I think the cable routing is done down the left side because the rear caliper, for a side pull brake is going to pull up on the left side.

The way your tandem is pictured makes sense; if you route the derailleurer cable housings so they cross in front of the head tube, they need to then cross agian before they hit the channels under the bb to get to the correct side.

I can see plus minuses. The crossing in front may lead to a smoother bend in the cable housing, but you've got paint rub to consider on the head tube, and I'm thinking the angle where the cable hits the cable routing at the BB may give back some or all of the advantage of cable routing at the head tube.

Bottom line, I doubt it makes any significant difference and is mostly an aesthetic choice.

waynesulak

I agree. It is also easy to change.

akexpress 

I did not notice any wear on the grooves after about 15k miles. they are now filled in when we converted to DI2

DubT

This is a location where I posted a picture of the way I routed our cables. The front derailleur cable crosses the head tube and then crosses under the boom tube I order to access the front derailleur.

The left brake lever activates the front brake as it does on nearly every bicycle that I have ever ridden. All of my motorcycles used the RH lever for the front brake.

https://www.bikeforums.net/showthread...=#post14104640

ksisler

chojn; The design looks to be for a fairly small bike. THus suggest there may be merit in staying with the smaller diameter wheels as that would reduce issues with toe strike and heel strike, while avoiding likely limitations on the headtube angle and related rake, etc.
Hope that helps
/Kerry

ksisler

DubT; Your pix shows really good routing IMHO because it is nicely tucked in, while clearly allowed full turns with no binding while using minimum cable length. Should always be the objective to my view.

Now for the handed-ness of it; I am a strong proponent of having the front brake under the right hand control if the owner is right handed and under the left hand if left handed... same for singles, doubles, triples. Rationale is that the riders strongest hand should be used on the brake which will be applying most of the stopping force and doing so with the maximum safety. I will admit to almost never using the rear brake except the drag brake on the tandems and that isn't a "stopping brake" and it is almost always on a barcon friction lever, no on a brake lever. /K

DubT

k, 99.99% of bicycle riders use the RH lever for the rear brake and the LH lever for the front brake. In my opinion using only the front brake could be problematic, for instance what happens when you grab a hand full of front brake and the road surface is slick. The front wheel can lock up, slip and down you go.

I have ridden bicycles for 60 years and I raced for around 15 years and I always use both brakes simultaneously. I also have ridden road motorcycles and competed in off road events on trials motorcycles. In both arenas it is critical to learn how to use both brakes effectively.

Do you ever ride a single and if so do you only use the front brake on it also?

cplager

This (99.99%) is certainly not true in Europe and many people who ride motorcycles switch them on bicycles.

But I just disagree about the strength of that one statement. I agree with the message.

ironhanglider

I find the discussion on brake technique interesting. On my single bike I use both brakes simultaneously but heavily biased towards the front brake. In good grip conditions and stopping in a straight line in a hurry I will use the front brake only as it will stop the bike faster than both brakes. (Yes I have tested it, as well as having won a few bets too). Under maximum braking my rear wheel is barely in contact with the ground (even with my weight back) and the slightest braking force will cause the rear to lock up, when that happens instincts take over to release the both brakes a bit and that is where you increase your stopping distance. However that is a pretty specific circumstance. When you are not braking at full force such as in less than ideal grip conditions or whilst cornering, there is more weight on the rear wheel and the rear brake does have some effect before it locks the wheel so I use more then.

Whilst this is all good single bike theory I find it to be different on a tandem where there is much more weight on the rear even at maximum braking. I use a significant amount of rear brake on a tandem, I find it hard to try and quantify the amounts due to different brake types between front and rear but it is probably about 40% of the total effort with my 95kg regular stoker and about 15% with my 3 year old as a stoker. I am also less likely to be braking at the maximum on the tandem since I try to be more conservative.

Cheers,

Cameron

ksisler

Dub; I would suggest that most American's ride their bikes in whatever way their first bike was setup at Walmart, etc., when their parents bought it for them way back when before Christmas day. Basically that is as you defined it; left hand on the front brake. My post was to posit the thought that the left hand configuration isn't necessarily ideal for everone.

What no one has covered in this specific thread was the interrelation between the configuration and the riding style and the braking style. It has been my experience that racers tend to do what is right for them and continue that forward if they ride otherwise, such as touring. That is probably best for all as it could be a real problem switching back and forth (which I always recommend not doing).

To close on your last question; yes I do ride a single regularly although it is not my preference (but stoker is not always available). When I ride single I ride the same as on a tandem or triple...mostly right braked and not much on the rear brake. Probably comes somewhat from my early experiences commuting on a single with only the front brake installed. Can discuss all that in below suggested thread.

When we have a new thread on the "how to brake" we can discuss at length what we do with the brakes (regardless of handedness). Since I would never grab a full hand of front brake on a slick road (nor could see how using the rear brake helps any in such a case), don't race bikes, don't ride motocycles and thus don't race them either, I am sure we will have a different view there, which is ok with me. We should consider in advance if the discussion then in about tandems or about singles and have it in the correct forum for ease of handling.
/K

merlinextraligh

Updates on the project?

ksisler

Merlin; I haven't seen a more recent post by the Chojin than late Jan 13. Might want to PM him to see if he is still growing it or if his is too busy riding to spend time on the computer....
/K

mrfish

Personally I would try and eliminate as many unknowns as possible if you are wanting to build one CF tandem. That will keep time manageable and minimise blind alleys. Then on your next tandem you might be more experimental. So that would involve:

1) Minor modifications to the geometry of a well-known good handing tandem which fits you
2) Copying the design of a jig using whatever material you know best, be it aluminium angle, plywood or steel girders
3) Buy tubes from ENVE, recommended tools
4) Buy in small parts from someone who sells them. Don't know who
5) Use known good epoxy system designed for this type of construction. Not hardware store epoxy.
6) Use tube to tube construction method to build it
7) Better still, arrange for a paid tutorial from someone who has proven skills

That will all cost more than a second hand Calfee I would imagine, but you will get something which is your own. As someone who taught myself to build model aeroplanes, helicopters and all sorts of other things and holds an M.Eng I don't think building a tandem is difficult per se, but it will takes time and experience to get it right and the consequence of getting it wrong mean that a professional approach is worth applying.

chojn1

Hi all,

First , my apology for the tardiness of this update. Work, our active travel schedule, and life in general got quite hectic last year. What little bit of free time I had was spent enjoying our weather - riding rather than building our bike. There were very little progress to report.

Now that the weather has turn cold and wet, I found myself with a little more bike building time. If anyone is interested, I'll post my progress updates. Since last I posted, I have completed the last carbon layers, bottle cage mounts, and cable stops. Here is the frame drying from the last clear coat:



The next challenge is to route the cables beneath the eccentric and rear bottom bracket. The regular bottom bracket cable guide is designed only for the two derailleur cables and does not have room for the rear brake cable. And I don't think anyone sells a guide for beneath the front eccentric. Any suggestions?

CJ

waynesulak

Very happy to read the update. Your frame looks well done.

It appears that it would be nice to have a cable guide that would allow the cables to clear the carbon clamps. One very simple solution is to use the Santana idea of a simple metal bar with three holes drilled to allow the cables and cable liner to pass through. You could bond a tall enough metal bar to allow the cables to clear the clamps.

A better solution might be to fabricate your own guide with three metal tubes bonded to the BB.

nfmisso

A block of acetal (aka DelrinŽ) would probably be better than a metal block, to prevent damage to the cables. If metal is preferred, use a copper alloy such as brass or bronze for its lubricious properties. Do NOT use aluminum as it will gall on the steel cables and jam up the works. Stainless on stainless is also not a good combination. Electro-less nickel plated metal would be a good choice.

chojn1

Thanks for the advice. I was about to pull out some aluminum tubes - that would have been a mistake. What about stainless steel cable on carbon fiber? I don't have any Delrin, but I have plenty of left over carbon fiber.

CJ

chojn1

I layered some carbon fiber patches overnight. I'll trim and carve them when I get home from work. Rather using tubes, I think I'll just cut groves in them. I am hoping the stainless steel cable will slide against carbon fiber groves without too much friction.